JP2015534005A5 - - Google Patents

Description

The high-lift latch restriction 24, the latch 200 is shown a high-lift event which engages the outer arm 12 0. When the valve is opened against the force biased by the valve spring 114, the latch 200 transmits the force from the inner arm 122 to the outer arm 120. When the force of the spring 114 is transmitted by the latch 200, the latch 200 is locked in its extended position. Under this condition, the hydraulic pressure applied to perform the OCV switch while attempting to switch from the high lift mode to the low lift mode locks the latch 200 and prevents it from retracting. It is not enough to win the power. This condition extends the entire switching window by allowing pressure to be applied before the basic lift motion 863 is initiated (FIG. 23) when the high lift event ends and the latch 200 becomes unloaded. is there. When the force on the latch 200 is released, the switching event can be started immediately.

Here, as shown in FIGS. 4 and 25A, the camshaft rotation and the movement timing of the latch 200 coincide with each other, and a load is applied to the latch 200 at one end, where the latch is partially on the outer arm 120. If only engaged, a critical shift may occur. Once the high lift event begins, the latch 200 may slip off the outer arm 120 . When this occurs, the inner arm 122 is accelerated by the force of the valve spring 114, causing a collision between the roller 128 and the low lift cam lobe 108. Critical shifts are undesirable because they cause momentary losses in the control of rocker arm assembly 100 and valve movement, and impact the system. The DVVL switching rocker arm was configured to respond to the occurrence of a critical shift for life.

Projectile impingement on the surface of the wires 396, 397 to form the torsion springs 134, 136, or “shot peening”, is used to apply residual compressive stress to the surfaces of the wires 396, 397. Next, the wires 396 and 397 are wound to become torsion springs 134 and 136 . Such shot peening allows the resulting torsion springs 134, 136 to accept greater tensile stress than equivalent springs formed without shot peening.

The diamond-like carbon coating (DLC) reduces friction, and at the same time, the slider pads 130 and 132 have the necessary wear and load characteristics, thereby enabling the illustrated switching rocker arm 100 to operate. As will be readily appreciated, the benefits of DLC coating can be applied to any part surface of this assembly or other assemblies (eg, pivot shaft surfaces 160, 162, on the outer arm 120 shown in FIG. 19). .

4.5.2 latch pin mechanism rocker arm assembly 1 00 of the latch pin mechanism 201, the high lift mode to the low lift mode, and, from the low lift mode to the high lift mode, provides a means for switching mechanically. The latch pin mechanism is normally in an unlatched state or can be configured to be in a latched state. Several preferred embodiments are described.

Here, as shown in FIG. 43, FIG. 47, and FIG. 48, the design and assembly changes of the individual parts and subassemblies generate a matrix of rush values that meet the switching timing specifications, and the required constants described above. The speed switching area can be reduced. For example, a self-aligning embodiment of one latch pin 200 includes a shape that requires a minimum latch rush 602 of 10 microns to function. Latch 200 Fixed improved is configured without self Alignment feature, it can be designed to require a latch rush 5 microns. This design change reduces the total lash by 5 microns and reduces the no lift 661 required for the valve lift profile 660.

The durability of the DVVL switching rocker arm is assessed by a combination of continuous performance (ie, proper valve opening and closing) and wear measurement. Wear is assessed by quantifying the loss of material on the DVVL switching rocker arm, especially the DLC coating, along the relative amount of mechanical lash in the system. As described above, it latches Rush (Figure 43) is required to allow movement of the latch pin between the inner and outer arms, when commanded by the engine electronic control unit (ECU), the high-lift mode And low lift mode operation. Increased rush on DVVL rocker arm by any reason, to reduce the available lift tooth ramp 661 (FIG. 48), a high acceleration occurs in the valve train. Wear specifications for mechanical lash are set to allow limited built-in parts to maintain the desired dynamic performance at the end of life.

For example, as shown in FIG. 43, wear between the contact surfaces of the rocker arm assembly changes the latch lash 602, the camshaft lash 610, and the resulting total lash. The wear that affects each of these values is as follows. 1) Wear at the interface between roller 128 (FIG. 15) and cam lobe 108 (FIG. 4) reduces total lash. 2) Sliding surface wear between the sliding surfaces, slider pads 130, 132 (FIG. 15) and cam lobes 104, 106 (FIG. 4) increases the total lash. 3) Wear between the latch 200 and the latch pad surface 214 increases total lash. Wear at the bearing interface reduces total lash, and wear at the latch and slider interface increases total lash. Overall wear, the total lash net is intended to be minimized over the life of the rocker arm assembly.

FIG. 17 shows a diagnostic window representing one switching cycle system for diagnosing valve closing displacement. When OCV is commanded by the control system, it moves the OCV armature, which is represented by OCV current tracking 881. The downstream hydraulic fluid flow in the OCV control gallery increases as shown by the pressure curve 880, which drives the latch pin and causes a change from a high lift state to a low lift state. .

Test changeover (switching) Durability switching endurance test of the lower system, the SRFF, from the latch state to the unlatched state, by operating 3 million times a cycle of returning to Soshitema was latched state, to evaluate the switching mechanism . The primary purpose of this test is to evaluate the latch mechanism. Since 50% of the test cycle is in the low lift mode, additional durability information about the torsion spring is obtained.

Idle Speed Endurance The idle speed endurance test simulates the critical lubrication conditions caused by the hydraulic pressure pulled and the high hydraulic fluid temperature. This test is used to evaluate the wear on the slider pad and bearing, the valve tip against the valve pallet, and the ball socket against the ball plunger. The lift state is kept constant at either high or low lift throughout the test. Total mechanical lash is measured at periodic inspection intervals and is the primary measure of wear.

A test of the valve train dynamics was performed to evaluate the performance of the valve train. This test was carried out at nominal and limit values for the total mechanical rush. The case of nominal values will be described. A speed sweep from 1000 rpm to 7000 rpm was performed and 30 valve events were recorded for each engine speed. By post-processing the dynamics data, the valve closing speed and valve bounce can be calculated. The strain gauges attached to the outer and inner arms of the SRFF show sufficient loading to prevent separation between valve train components or HLA “pump-up” at all engine speeds. Pump-up occurs when the HLA compensates for valve bounce or valve deflection that leaves the valve open on the camshaft base circle. In order to provide an understanding of the distribution over a range of engine speeds, minimum, maximum and average closing speeds are shown. The high lift closing speed is shown in FIG. High lift closure rate is meet the design goal (target). The range of values varies approximately by 250 mm / s between the minimum and maximum values at 7500 rpm, while staying reliably within the target range.

Cast Iron Camshaft Results In the first test , a cast iron camshaft lobe was used to compare the slider pad surface finish and the two angular alignment configurations. The results are summarized in Table 2. The table summarizes the combinations of slider pad groove angles and surface finish conditions tested on cast iron camshafts. Each combination was tested at maximum load conditions and 125% of maximum load conditions. The value listed is the number of engine lifetimes achieved in each combination during the test.

Steel camshaft test results In the next set of tests, steel camshaft lobes were used. A summary of the combinations tested and the results are summarized in Table 3. The camshaft lobe was tested under four different conditions: That is, (1) a flat grinding surface finish, (2) class U down with lobes, finish grinding surface (3) with minimum crowned lobes, polished surface, (4) at nominal crowned lobes, polished Finished surface. The slider pad on the coupon was polished before DLC coating and tested at the following three angles. That is, (1) flat (groove angle below 0.5 degrees), (2) groove angle of 0.2 degrees, and (3) groove angle of 0.4 degrees. The load on all camshafts was set at the maximum design level or 125% of the maximum design level.

Test samples of flat steel camshaft lobe and 0.4 ° open destination angle of coupons ground at 125% of the maximum design load did not exceed 1 life. Samples tested at maximum design load lasted one life, but a similar effect was seen on the coating. Samples as flat as 0.2 degrees were better but did not exceed 2 lives.

After this test, grinding, flat, steel properties camshaft lobe, and 0.2 degrees included angle of coupons, and tested in flat coupons were. The time before observing the coating loss was 1.6 life for the 0.2 degree sample. Flat coupon achieved a slightly longer 1.8 life. The pattern of DLC loss for the flat sample was non-uniform and the maximum loss was outside the contact patch. That there is outside the loss of the coating of the contact patch, it indicates that stress experienced by the slider pads was nonuniform I were I to its width. This phenomenon is known as the “edge effect”. A solution to reduce the stress at the edges of two aligned elements is to add a crown-shaped profile to one of the elements. In an application using SRFF, a profile with a crown is added to the camshaft.

This section describes the development of a slider pad manufacturing method from coupons to SRFL outer arms.

Here, referring to FIG. 30A, FIG. 30B, and FIG. 99, the torsion spring 1124 is composed of a substantially trapezoidal wire 397. The trapezoid is configured such that the wire 397 can be deformed into a substantially square shape when a force is applied during the winding process. After the torsion spring 1124 is wound, the resulting wire shape is similar to the first wire 396 with a substantially square cross-sectional shape. The two torsion spring embodiments shown in FIG. 99 are shown as cross-sections of a plurality of coils 398, 399. In a preferred embodiment, the wire 396 has a rectangular cross-sectional shape with two long sides, shown in this example as vertical sides 402, 404, and a top side 401 and a bottom side 403. The ratio of the average length of the top side 401 and the bottom side 403 of the coil to the average length of the side 402 and the side 404 can be any value less than one. This ratio results in greater stiffness along the bending coil axis 400 than a spring wound using a circular wire with a diameter equal to the average length of the top side 401 and bottom side 403 of the coil 398. In another embodiment, the cross section of the wire has a generally trapezoidal shape with a long top side 401 and a short bottom side 403.

In the configuration of the SRFF-1L 1100, consideration is given to pumping up when the system is in the no-lift mode. A situation in which the inner arm 1108 does not return to a position where the latch 1202 can be re-engaged with the inner arm 1108 due to pumping up of the DFHLA 110 when the S R FF-1L 1100 is in the no-lift mode may occur.

Claims (20)

A rocker arm that engages a cam with a single lift lobe per valve,
An outer arm including a first outer side arm and a second outer side arm;
A first inner side arm, a second inner side arm, and an inner arm including a cam contact member configured to transfer motion from a single lift lobe of the cam to the rocker arm, the inner arm comprising: The cam contact member is disposed between the first inner side arm and the second inner side arm, and is disposed between the first outer side arm and the second outer side arm.
A pivot shaft that secures the inner arm to the outer arm, the pivot shaft being configured to allow rotational movement about the pivot axis relative to the outer arm of the inner arm;
A rocker arm, further comprising at least one biasing spring fixed to the outer arm and biased into contact with the cam contact member.   The rocker arm includes a latch that selectively secures the inner arm to the outer arm and selectively allows lost motion movement about a pivot axis relative to the outer arm of the inner arm. Rocker arm as described in. The rocker arm further includes a first end and a second end, the pivot shaft is disposed close to the first end, and the biasing spring is attached to the outer arm close to the second end, and the cam contact portion 2. The rocker arm according to claim 1, wherein the material is disposed between the pivot shaft and the biasing spring.   The rocker arm of claim 1, wherein the latch includes a surface that defines an orientation of the latch and prevents rotation of the latch.   The at least one biasing spring includes at least one torsion spring secured to the outer arm, the at least one torsion spring having a spring arm in biasing contact with the cam contact member. The rocker arm described.   The at least one biasing spring includes first and second biasing springs, the first biasing spring is fixed to the first outer arm, and the second biasing spring is the second outer arm. The rocker arm according to claim 1, wherein the first and second urging springs are urged into contact with the cam contact member.   The rocker arm according to claim 1, wherein the cam contact member includes a bearing attached to a bearing shaft.   The rocker arm according to claim 1, further comprising a valve pad attached to the pivot shaft.   The rocker arm according to claim 1, wherein the at least one biasing spring includes a wire having a substantially square or substantially trapezoidal cross section.   The rocker arm according to claim 1, wherein the at least one biasing spring includes a high-strength alloy steel that is treated to apply residual compressive stress to the surface of the at least one biasing spring. A rocker arm that engages a cam having a single lift lobe,
An outer arm including a first outer side arm and a second outer side arm;
An inner arm including a first inner side arm and a second inner side arm, the inner arm being disposed between the first outer side arm and the second outer side arm,
A cam contact member configured to transfer motion from a single lift lobe of the cam to the rocker arm, the cam contact member disposed between the first inner arm and the second inner arm; Attached to the bearing shaft,
A pivot shaft that secures the inner arm to the outer arm, the pivot shaft being configured to allow rotational movement about the pivot axis relative to the outer arm of the inner arm;
A rocker arm, further comprising at least one biasing spring fixed to the outer arm and biased into contact with the cam contact member.   The at least one biasing spring includes first and second torsion springs attached to the first and second outer arms, and the first and second torsion springs are in biasing contact with the cam contact member. The rocker arm according to claim 11.   The respective end portions of the first and second torsion springs are mounted in the first and second slot portions on the side surface of the cam contact member, and are biased with the cam contact members of the first and second torsion springs. The rocker arm according to claim 12, wherein contact is maintained.   The rocker arm further includes a first end and a second end, the pivot shaft is disposed close to the first end, and the biasing spring is fixed to the outer arm close to the second end, and the cam contact member The rocker arm according to claim 11, wherein the rocker arm is disposed between the first end and the second end.   The outer arm further includes a latch that selectively secures the inner arm relative to the outer arm and selectively allows lost motion motion about a pivot axis relative to the outer arm of the inner arm. Rocker arm as described in.   The rocker arm of claim 15, wherein the outer arm further includes a port for transmitting fluid pressure from a working fluid source to the latch.   The rocker arm according to claim 11, wherein each of the first and second outer side arms includes a pivot shaft opening, a bearing shaft slot, a clip opening, and a spring mounting.   The rocker arm according to claim 11, wherein the at least one biasing spring includes a wire having a substantially square or substantially trapezoidal cross section.   12. The rocker arm according to claim 11, wherein the at least one biasing spring includes a wire having a cross section having a length and a width, and the ratio of the average length of the cross section to the average width of the cross section is greater than one. .   12. A rocker arm according to claim 11, wherein the at least one biasing spring comprises high strength alloy steel that has been treated to apply residual compressive stress to the surface of the at least one biasing spring.

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